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Message-ID: <d8c171ce-6dfe-e9e5-5673-8443cfec5f01@kernel.dk>
Date: Wed, 22 Aug 2018 08:27:04 -0600
From: Jens Axboe <axboe@...nel.dk>
To: Holger Hoffstätte <holger@...lied-asynchrony.com>,
Anchal Agarwal <anchalag@...zon.com>
Cc: fllinden@...zon.com, sblbir@...zon.com, msw@...zon.com,
linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] blk-wbt: Avoid lock contention and thundering herd issue
in wbt_wait
On 8/22/18 6:54 AM, Holger Hoffstätte wrote:
> On 08/22/18 06:10, Jens Axboe wrote:
>> [...]
>> If you have time, please look at the 3 patches I posted earlier today.
>> Those are for mainline, so should be OK :-)
>
> I'm just playing along at home but with those 3 I get repeatable
> hangs & writeback not starting at all, but curiously *only* on my btrfs
> device; for inexplicable reasons some other devices with ext4/xfs flush
> properly. Yes, that surprised me too, but it's repeatable.
> Now this may or may not have something to do with some of my in-testing
> patches for btrfs itself, but if I remove those 3 wbt fixes, everything
> is golden again. Not eager to repeat since it hangs sync & requires a
> hard reboot.. :(
> Just thought you'd like to know.
Thanks, that's very useful info! I'll see if I can reproduce that.
--
Jens Axboe
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